High pressure storage tank inlet fiting and muffler assembly



Dec. 13, 1960 R. w. GRAHAM HIGH PRESSU RE STORAGE TANK INLET FITTING AND MUFFLER ASSEMBLY Filed Dec. 19, 1958 lllll iIIIIldiIII Z gaff/4463a? WJZ/ TORNEY United States Patent HIGH PRESSURE STORAGE TANK INLET FITTING AND MUFFLER ASSEMBLY Robert W. Graham, Birmingham, Mich, assignor to General Motors Corporation, Detroit, M1ch., a corporation of Delaware Filed Dec. 19, 1958, Ser. No. 781,743

3 Claims. (Cl. 181--36) This invention relates to vehicle air suspension apparatus and more particularly to high pressure storage tank mufiler assemblies.

In the copending application Serial No. 677,391, Joseph B. Depman, entitled Surge Mutfler for Air Storage Tank, filed August 9, 1957, it has been proposed to provide a cartridge type muffler assembly capable of insertion into the high pressure storage tank through the inlet thereof for the purpose of diffusing the air compressor discharge pulse so that the pulse component causing tank resonance is filtered out. While a device of the type disclosed therein proves highly effective for the purpose intended, because of the requirement of extreme compactness, progressive deterioration in efficiency may occur due to gradual build-up of solid and semi-solid contaminants carried by the air delivered from the compressor. i

An object of the present invention is to provide an improved and simplified muffler assembly.

Another object is to provide an improved cartridge type mutfler assembly adapted for insertion into an air suspension high pressure storage tank through the inlet thereof.

A further object is to provide a self-cleaning mufller assembly.

Still a further object is to provide a mufller assembly which is so constructed that movement of air therethrough induces physical motion of the muffler sutficient to dislodge accumulated deposits thereon.

Yet another object is to provide a muffler comprising a single flexible tubular element having normally closed slit-like openings formed in the wall thereof which alternately open and close under the influence of pulsing air pressure delivered to the interior thereof.

A still further object is to provide a device of the type described which is incorporated into an air storage tank inlet fitting.

Yet a further object is to provide a muffler assembly of the stated character including an air inlet fitting having a relatively small diameter tightly wound coil spring connected thereto in such a manner that the interior of the spring forms a continuation of the inlet fitting, the free end of the spring being closed so that alternating air pressure increases interiorly of the spring act to exert an expanding force causing the coils to separate axially and allow diffused discharge of the air.

Yet another object is to provide an air inlet fitting having a mufiler assembly of the type described including a check valve assembly positioned immediately upstream thereof.

These and other objects, advantages, and features of the invention will become more fully apparent as reference is had to the accompanying specification and drawings wherein:

Fig. l is a fragmented elevational view, partly in section and with parts broken away. illustrating a high pressure storage tank having secured thereto an inlet fitting and mufller assembly incorporating the present invention;

Fig, 2 is a fragmentary view of a portion of the muffler assembly shown in Fig, 1 illustrating a modification of a portion thereof;

Fig. 3 is a fragmentary elevational view, partly in section and with parts broken away, illustrating a preferred form of muffler construction in accordance with the invention; and

Fig. 4 is an enlarged end elevational view looking in the direction of arrows 4-4 of Fig. 3.

In Fig. 1, there is shown one form of the invention wherein reference numeral 2 designates a high pressure air storage tank having an integral flanged nipple 4 formed with internal threads 6. The internal threaded portion 6 of flange 4 is adapted to receive an inlet fitting 8 having an inner end portion 10 formed with external threads 12 and internal threads 14. Fitting 8 is provided with an inlet passage 16 which extends axially therethrough and at its outer end is formed with an externally threaded portion 18 which is engaged by a cylindrical casing 20 having a check valve assembly 22 disposed therein. Assembly 22 is directionally oriented so that movement of air through the inlet passage 16 into tank 2 causes unseating of the valve, while movement of air in the opposite direction causes seating thereof. It will be understood that cylindrical fitting 20 is intended for connection by a suitable conduit, not shown, to the discharge side of an air compressor, also not shown.

In accordance with the present invention, the inner end 10'of fitting 8 has connected thereto a flexible tubular member in the form of a relatively small diameter coil spring 24 wound so that each successive coil yieldingly abuts the adjacent coil. As seen in Fig. l, the first several coils at the inner end 26 of the spring are rotated or threaded into the internal threads 14 of fitting 8 until the first coil of the spring abuts the shoulder 28 at the base of threads 14. At its opposite or free end, spring 24 is plugged by a cylindrical member 30 formed of metal, rubber. or other suitable material which is surroundingly embraced by the last several coils of the spring.

It will be apparent that during periods in which the air comp essor is not operating, spring 24 will maintain the closed coil relationship shown. However, when the pressure in tank 2 is depleted by operation of the systern with which it is associated, air supplied by the compressor. not shown, displaces check valve 22, emerges into passage 16 of fitting 8, and enters the cylindrical cavitv defined by coil spring 24-. As soon as air pressure therein exceeds the springs static tension, each of the individual coils thereof will expand longitudinally and separate slightly (as shown in exaggerated form in Fig. 2\ providing a more or less continuous helical slit through which air may pass into the interior of tank 2. Although the internal air pressure in the spring element is determined by the compressor discharge pressure, because of the continuous tension exerted by the spring, the rate of discharge of air from inside the spring through the co l separations will occur at a rate somewhat slower than the pulse rate of the compressor discharge and will, therefore. modify the character of the discharge pulse sufficientlv to prevent excitation of tank resonance.

In addition to its acoustical function, operation of a device according to the present invention produces a selfcleaning action which greatly increases tolerance to induction of solid contaminants carried by the air discharge of the compressor. As previously stated, induction of air from the compressor results in alternating axial flexing of the individual coils of spring 24. This flexing mechanical movement causes repeated impact between the individual coils which prevents particles from adhering to the coils or causing the coils to adhere to each other. Therefore, such contaminants as are inducted tend to remain finely divided or are subsequently broken up by coil impact so that they are readily discharged through the separations between the coils.

In Fig. 2, there is shown a modification of Fig. 1 wherein the cylindrical element 34 which plugs the free end of spring 24 is formed with a calibrated orifice 36 providing limited open communication between the interior of the coil spring and the interior of the tank. It will be apparent that variation in the size of orifice 36 will permit greater latitude in the static tension specification of coil spring 24 as well as affording a simple and convenient means of tuning the muffier for optimum filtering of objectionable pulse characteristics of the compressor.

In Fig. 3, there is shown a preferred embodiment of the invention wherein the mufiier takes the form of a flexible tubular element 38 of rubber-like material such as neoprene. The inner end 40 of tube 38 surroundingly engages the outer end of a cylindrical nipple 42 which is press fitted in counterbore 44- in the threaded inner end 6 of fitting 8 aligned with passage 16. A circular clamp ring 46 tightly embraces the outer periphery of end 40, securing the latter against axial movement relative to nipple '42. At its outer free end, tube 38 is plugged by a cylindrical member 48 which is retained therein by a second circular clamp ring 58. In the embodiment shown, discharge of air from the interior of tube 38 into the interior of tank 2 is accommodated by a plurality of lanced slits 52 which are disposed at equally spaced intervals axially of the tube and indexed circumferentially uniformly so that discharge pressure will radiate substantially equally in all directions and thus prevent whipping motion of the free end of the tube. In operation, the embodiment of Fig. 3 performs essentially the same as that described with reference to the embodiment of Fig. 1. Thus, introduction of increased pressure internally of the tube causes the latter to inflate and thus extend both axially and radially causing the slits to open and permit the emergence of air into the tank. Similarly, the continual flexing of the wall of tubular element 38 responsive to pulsing fiow of air inhibits build-up of solid contaminants interiorly thereof. However, in addition to operational characteristics common to the embodiment of Fig. 1, it has been found that the imperforate portion of tube 38 tends to expand or balloon under the influence of air pulses, providing a surge chamber efiect which significantly improves mufiler effectiveness.

It will be understood that the modification shown in Fig. 2 may also be incorporated in the structure of Fig. 3.

From the foregoing it will be seen that a novel and extremely simplified inlet fitting and mufiier assembly has been provided. It is to beparticularly noted that constructions according to the invention are not only extremely simple to fabricate and assemble, but also possess functional characteristics which virtually preclude degradation of initial efficiency of operation.

While several embodiments of the invention have been shown and described, it will be apparent that numerous additional changes and modifications may be made therein. Therefore, it is to be understood that it is not intended to limit the invention to the embodiment shown, but only by the scope of the claims which follow.

I claim:

1. A muffier assembly comprising, a rubber-like tubular member having normally closed transverse slits formed in the wall thereof at axially spaced intervals along a helical path, an inlet fitting including a check valve assembly communicating with one end of said tubular member, and a closure secured in the other end of said member.

2. For use in a high pressure storage tank, a muifler assembly comprising, a rubber-like tubular member having normally closed transverse slits extending through the wall thereof, said slits being equally spaced axially and indexed circumferentially uniformly, an inlet fitting including a check valve assembly communicating with one end of said tubular member, and a closure secured in the other end of said member, said closure having a fixed orifice of predetermined size extending therethrough and communicating with the interior of said member.

3. The structure set forth in claim 2 wherein an imperforate portion of said tubular member extends through at least half the length of said tube from the end thereof adjacent said fitting.

References Cited in the file of this patent UNITED STATES PATENTS 181.288 Shaw Aug. 22, 1876 191,545 Parry June 5, 1877 362,841 Hyatt May 10, 1887 1,761,471 Forstel June 3, 1930 2,136,098 Browne Nov. 8, 1938 2,283,607 Ludwig May19, 1942 2,771,320 Korwin Nov. 20, 1956 FOREIGN PATENTS 20,266 Denmark June 11, 1915 764,504 France Mar. 5, 1934 539,999 Italy Feb. 27, 1956 

